Prior to the fall of Quel'Thalas in the Third War, Saji Dawntreader - brother to the patriarch of the house and regent of Quel'Belore, Archidian Dawntreader - had a violent disagreement with the Patriarch on how the house was run. Without recourse, Saji and those who were loyal to his ideals for the Dawntreader line split away, exiling themselves from Quel'Belore and the rest of the family.
The Third War
When Arthas invaded, Archidian still reeled from the betrayal of his beloved brother, but could not find himself to hold such a grudge with the fate of their entire race hanging in the balance. Struggling to pull the bits and pieces together from the horrific genocide, the Duke departed his wounded duchy to seek out his other brother, Vanis Dawnsorrow with a mission in mind. All remaining cavalry from Aran'Thuilode were ordered to ride out in search of Saji and his new 'family', but to the collective dismay of the remaining Dawntreaders - now adopting the surname Dawnsorrow - they only met with a destroyed settlement, and the Scourge. A battle ensued, with both Archidian and Vanis leading the charge of Thuilodian cavalrymen, yet fate did not wish the decorated and beloved Patriarch to survive. Archidian was struck down, as well as two-thirds of the cavalry, in pursuit of making his family whole once more after such a devastating blow was struck to the Quel'dorei people.
Vanis and the last third of his men combed the ruins of the little village, intent to fulfill the dying wish of his brother, but found nothing. Defeated, demoralised, dejected and heartbroken, the Last Lord Dawnsorrow rode back with his brother's body to be entombed in the family mausoleum.
Down, But Not Out
As it would happen, Saji was not fated to die like his brothers were meant to believe. The news of the Elfgates under siege had him relocate from that little village to the capitol of Silvermoon City, where he employed the skills of himself and those under him; intrigue, stealth, and assassination. With the power and backing of a mysterious organisation in Silvermoon known - and whispered only as - The Council, Saji's sect of the line became, and bred those of a shadier lifestyle. This proved invaluable during the Third War, as the splinter sect worked in tandem with the Outrunners and Scouts that reported on the movements of the Scourge army.
New Life, New Name, New Traditions
Saji had not been idle in forming his new house and setting tradition with the lovely Adete Cross, of which they boasted twins, Fellamor and Luthorin. He would go onto have children with another, Avinyth Vaneal; a daughter, Ayami Cross. A tradition was established thence, that women born into the Dawnsorrows of the Nightfall would be given the surname Cross, and the men would be Dawnsorrow. For this, the banner of the family would alternate; House Cross if a woman reigned, House Dawnsorrow of the Nightfall if a man did.